Posts tagged ‘Rubidium Standard’

Keithley 775A Programmable Counter TCXO Repair

In my last post, I did a teardown of the Keithley 775A programmable counter/timer. And while feeding a 10 MHz signal from my Rubidium frequency standard, I noticed that the measured frequency was significantly lower (9.9981 MHz) than the nominal 10 MHz reading and could not be compensated by adjusting the TCXO fine adjustment screw alone. My suspicion quickly turned to the temperature controlled crystal oscillator (TCXO). Continue reading ‘Keithley 775A Programmable Counter TCXO Repair’ »

Jitter Measurement of the Pulse Width Expanded 1PPS Output

In my previous blog posts, I did a teardown of the Symmetricom/Datum 8040 Rubidium frequency standard and modified the 1PPS output by expanding the pulse width from just around 10µs to roughly 50% duty cycle. There were some questions regarding the clock jitter introduced by the 555 monostable circuit. So let’s take a more detailed look in this post. Continue reading ‘Jitter Measurement of the Pulse Width Expanded 1PPS Output’ »

Datum/Symmetricom 8040 Rubidium Frequency Standard Teardown

I finally got my hands on a Rubidium frequency standard. I have been wanting to get one of these for my lab for quite some time now but have not encountered a good one at a reasonable price. Most rubidium oscillator modules on the second hand market these days come from decommissioned equipment used in cell towers. A good used lab grade rubidium standard is even more expensive. Continue reading ‘Datum/Symmetricom 8040 Rubidium Frequency Standard Teardown’ »